Valve announces a Steam Workshop sale in celebration of the success of the Portal 2 Perpetual Testing Initiative:

Valve, creators of best-selling game franchises (such as Half-Life and Counter-Strike) and leading technologies (such as Steam and Source), today announced the early findings of the Portal 2 Perpetual Testing Initiative.

Released just days ago, The "Perpetual Testing Initiative" has already resulted in the creation and publishing of over 35,000 user-created maps, collectively consumed via more than 1.3 million downloads.

To celebrate the launch, Steam is holding a Weekend Workshop Sale offering Portal 2 for 66% off, Elder Scrolls V: Skyrim for 33% off, and many of this year's Team Fortress 2 Workshop Items available for 50% off their regular price.

The Perpetual Testing Initiative allows players to easily create, share, and play Portal 2 puzzles. The Initiative comes with a simplified Puzzle Maker that allows that creation of mind-bending puzzles without ever leaving the game.

The Puzzle Maker directly publishes maps to the Steam Workshop where users may browse, vote on, and select to play them. Selected puzzles are automatically downloaded and installed inside Portal 2.